I thought my Rev3's diff was missing parts too. It should be put together like this. At least this is how I had mine, before I got my IRS diff. Bearing in the axle carrier,diff,ring,gear,ring,bearing inside ,hub, outside bearing, then the washer and finally the plastic nut. Try it like that. I think that is how I had it together. I don't remember for sure. If I were you upgrade to an IRS diff, it works a lot better, but it's not a neccessity.